Assembling of G-strands into novel tetra-molecular parallel G4-DNA nanostructures using avidin–biotin recognition

We describe a method for the preparation of novel long (hundreds of nanometers), uniform, inter-molecular G4-DNA molecules composed of four parallel G-strands. The only long continuous G4-DNA reported so far are intra-molecular structures made of a single G-strand. To enable a tetra-molecular assembly of the G-strands we developed a novel approach based on avidin–biotin biological recognition. The steps of the G4-DNA production include: (i) Enzymatic synthesis of long poly(dG)-poly(dC) molecules with biotinylated poly(dG)-strand; (ii) Formation of a complex between avidin-tetramer and four biotinylated poly(dG)-poly(dC) molecules; (iii) Separation of the poly(dC) strands from the poly(dG)-strands, which are connected to the avidin; (iv) Assembly of the four G-strands attached to the avidin into tetra-molecular G4-DNA. The average contour length of the formed structures, as measured by AFM, is equal to that of the initial poly(dG)-poly(dC) molecules, suggesting a tetra-molecular mechanism of the G-strands assembly. The height of tetra-molecular G4-nanostructures is larger than that of mono-molecular G4-DNA molecules having similar contour length. The CD spectra of the tetra- and mono-molecular G4-DNA are markedly different, suggesting different structural organization of these two types of molecules. The tetra-molecular G4-DNA nanostructures showed clear electrical polarizability. This suggests that they may be useful for molecular electronics

A new approach for the isolation of biologically active compounds by affinity chromatography: Isolation of trypsin

Digitalitzat per Artypla

Polyethylene imine-based receptor immobilization for label free bioassays

Polyethylene imine (PEI) based immobilization of antibodies is described and the concept is proved on the label free assay of C-Reactive Protein (CRP). This novel immobilization method is composed of a hyperbranched PEI layer which was deposited at a high pH (9.5) on the sensor surface. The free amino groups of PEI were derivatized with neutravidin by Biotin N-hydroxysuccinimide ester and the biotinylated anti-CRP antibody immobilized on this layer. Direct binding assay of recombinant CRP was successfully performed in the low μg/ml concentrations using a label free optical waveguide biosensor

Meaning in life among adolescents: Factorial invariance of the Purpose in Life Test and buffering effect on the relationship between emotional dysregulation and hopelessness

Objective: The purpose of the present study was threefold: first, to analyse the psychometric properties of a 10‐item Spanish version of the Purpose in Life Test, which assesses meaning in life (MiL), in a sample of community adolescents; second, to analyse the differences between the age and gender groups; and third, to analyse whether MiL buffers the relationship between emotional dysregulation and hopelessness. Method: Participants were 1,599 adolescents from 12 to 19 years old, M = 15.69, SD = 2.14. The Purpose in Life Test‐10 Items, the Beck Hopelessness Scale, and the Difficulties in Emotional Regulation Scale were used. Results: A nine‐item version showed good fit, psychometric properties (internal consistency, construct, and concurrent validity), and factorial invariance across gender and age (12-15 years/16-19 years). Difference in MiL between boys and girls was not significant, whereas between age groups was significant. MiL had a strong buffering effect on the relationship between emotional dysregulation and hopelessness. Discussion: It is desirable to promote the sense of MiL in adolescents. MiL plays a significant and strong mediator role in the relationship between emotional dysregulation and hopelessness, reinforcing the positive role of MiL in mental health and as a resource for facing adversity